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Answer the following. (Science 2023 31/1/1 Q35)

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ScienceCBSE Class 10 · Board exam 2023, set 31/1/1 · 5 marks · Long answer

CBSE Class 10 Science 2023: question 35

Set in the CBSE Class 10 board exam of 2023, paper 31/1/1, section D, question 35, for 5 marks. Try it first; the hints and our step-by-step solution are below.

Q35 · 5 marks · Long answerHow do Organisms Reproduce?

Answer the following.

  1. (a)

    Name the parts of a bisexual flower that are not directly involved in reproduction.

    0 marks
  2. (b)

    Differentiate between self pollination and cross pollination. List any two significance of pollination.

    0 marks
  3. (c)

    What is the fate of ovules and ovary after fertilization in a flower ?

    0 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/1/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

The essential parts of a flower are stamens and carpels. Which whorls are left?

Hint 2

Compare where the pollen ends up: the same plant or a different plant.

Hint 3

Think about what you find inside a fruit, and which part of the flower it came from.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. (a) The parts of a bisexual flower not directly involved in reproduction are the sepals (calyx)

    ½ mark

  2. and the petals (corolla). Stamens and pistil are the reproductive parts.

    ½ mark

  3. (b) Self-pollination: pollen grains are transferred from the anther to the stigma of the same flower, or of another flower on the same plant.

    1 mark

  4. Cross-pollination: pollen grains are transferred from the anther of a flower on one plant to the stigma of a flower on a different plant of the same species, by agents such as wind, water, insects or birds.

    1 mark

  5. Significance 1: pollination brings the male gamete to the female part, which leads to fertilisation and seed formation.

    ½ mark

  6. Significance 2: cross-pollination brings genetic variation into the offspring. Pollination also stimulates fruit development.

    ½ mark

  7. (c) After fertilisation, the ovules develop into seeds

    ½ mark

  8. and the ovary develops (ripens) into the fruit.

    ½ mark

Answer: (a) Sepals (calyx) and petals (corolla); (b) Self: pollen to stigma of the same flower or another flower of the same plant; Cross: pollen to stigma of a flower on a different plant; significance: leads to fertilisation and seed formation, brings variation, stimulates fruit formation; (c) Ovules become seeds, ovary becomes fruit

Where the marks are

  • Sepals/calyx (½ mark)
  • Petals/corolla (½ mark)
  • Correct description of self-pollination (1 mark)
  • Correct description of cross-pollination (1 mark)
  • Any two significances, e.g. seed formation, fruit development, variation, leads to fertilisation (½ + ½ marks)
  • Ovule becomes seed (½ mark)
  • Ovary becomes fruit (½ mark)

Revise the chapter

Practise this chapterBoard-style questions from How do Organisms Reproduce?, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 31/1/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.